This project encompasses four areas of investigation based on a core sample of 65 middle-class families, each with a first-born infant, as well as additional participants to address specific questions. Procedures include observations of mother-infant and mother-father-infant interaction, interviews, assessments of child temperament, and structured laboratory assessments of the parent-infant attachment relationship. The first area of inquiry concerns the effects of maternal workforce participation on the child's early experience in the home environment. Included are analyses of parent-infant interaction in families with employed or homemaker mothers, more detailed observations of mother-infant interaction in the home both prior to and after mothers resume employment, and laboratory observations of toddlers and either employed or homemaker mothers. A second area concerns longitudinal stability and change of parent-infant interaction rates for the sample as a whole and as a function of various contrasting circumstances such as characteristics of the child or parent as well as levels of social engagement of the parents. The third area concerns the parent-infant attachment relationship its antecedents including quality of parent-infant interaction and the child's separation experiences, and the developmental consequences of contrasting qualities of attachment. A unique feature of this project is that the attachment assessment and the child's separation history are procedures common to several different samples, allowing coordination and replication of several research questions. The final area is a comparison of parent-infant interaction in families that experienced either cesarean or vaginal childbirth, as well as a substudy of families in which cesarean birth occured when the expectant father was present with the mother or not permitted to be with her.